Phase changing device for automobile engine

ABSTRACT

Objects The invention provides a phase changing device for automobile engine capable of preventing an unanticipated change in phase angle between the middle rotor and the camshaft of the device caused by a disturbing torque while preventing frictional wear of the inner circumferential walls of groove guides and avoiding generation of axial thrusts of links of the device. 
     Means for Solving the Problems A phase changing device for automobile engine, having a drive rotor, an middle rotor, and a control rotor, all arranged to rotate about a common rotational axis, the device controlling the control rotor so as to vary the relative phase angle between the drive rotor and middle rotor. The device comprises: curved first guide grooves formed in the control rotor, each groove skewed with respect to a circumference of a circle centered at the rotational axis; oblique guide grooves each groove formed in the middle rotor and extending at an angle with respect to a radius crossing the groove; second guide grooves formed in the drive rotor and skewed with respect to the circumference of a circle centered at the rotational axis, block sections each extending along, and movable in, the respective first guide; first slide members each protruding from the respective block section for engagement with, and for movement in, the respective skewed guide groove; and phase varying members each having a second slide member that extends through an escape groove formed in the middle rotor and engages the respective second guide groove so as to move in the second guide groove.

TECHNICAL FIELD

The present invention is directed to a phase changing device for varyingopening-closing timing of valves of an automobile engine by means of atorque means for providing the rotary drum of the engine with a torqueto vary the rotational phase of the camshaft relative to a sprocket ofthe engine.

BACKGROUND ART

There has been known a valve timing control device of this type, asdisclosed in Patent Document 1 cited below. In the device of the PatentDocument 1 a drive plate 3 driven by the crankshaft of the engine isassembled such that the drive plate 3 is rotatable relative to a flangering 7 coupled to the camshaft 1 of the device. Integrally mounted tothe camshaft 1, ahead of the drive plate 3, are a lever shaft 10 havingthree levers 9 and a hold ring 12, which are securely fixed to theflange ring 7 with a bolt 13. Rotatably mounted on the hold ring 12 viaa thrust bearing 28 is a middle rotor 23 ahead of the lever shaft 10.

A link 14 is rotatably connected at one end thereof to each of the threelevers 9 with a pin 15. Formed at the other end of the link is an axialreceptacle hole 16 for receiving therein movable member 17. Formed inthe front end of the drive plate 3 is a radial slot 8 (serving as aradial guide). Formed on the rear end of the middle rotor 23 are threespiral slots 24 each spiraling in the direction of rotation of the driveplate 3 with decreasing radius. The movable member 17 are provided atthree positions in association with the three corresponding spiral slots24. Each of the movable member 17 has retainers 19 and 21 for rotatablyholding balls 18 and 20 in the respective radial slot 8 and spiral slot24 via a leaf spring 22.

Provided on the front end of the middle rotor 23 is a permanent magnetblock 29 having N- and S-poles that alternates along the circumferenceof the rotor 23. Arranged in front of the permanent magnet block 29 is ayoke block 30 having first pole tooth ring 37 and second pole tooth ring38 for generating different magnetic poles when electromagnetic coils33A and 33B are energized. The magnetic poles of the pole tooth rings 37and 38 are switched on and off in a given switching pattern by themiddle rotor 23 so as to apply changing magnetic forces on the permanentmagnet block 29 to rotate the drive plate 3 relative to the camshaft 1.The rotation of the drive plate 3 is terminated by ending switching ofthe polarities.

As the middle rotor 23 is angularly advanced than the drive plate 3 inthe rotational direction R (referred to as angularly advancingdirection) under the polarity switching of the polar tooth rings 37 and38, the balls 18 and 20 of the movable member 17 are displaced radiallyoutwardly in the respective radial slot 8 and spiral slot 24. Then, thelever shaft 10 is retarded than the drive plate 3, that is, rotated inthe angularly retarding direction (opposite to the rotational directionR of the drive plate 3), thereby rendering the rotational phase of thecrankshaft and camshaft 1 retarded in the angularly retarding direction.On the other hand, when the polarity switching pattern of the polartooth rings 37 and 38 is changed so as to delay the middle rotor 23 inthe angularly retarding direction, the movable member 17 is displacedradially inwardly, thereby rendering the rotational phase of thecrankshaft and camshaft changed in the angularly advancing direction.

During operation, the camshaft 1 is subjected to reactions of the valvesprings, which reaction cause disturbing torques on the camshaft. Suchdisturbing torques may cause unexpected angular displacements of thedrive plate 3 relative to the camshaft 1. The device of the PatentDocument 1 has a self-lock mechanism in which the camshaft 1 isimmovably locked to the drive plate 3 via the link 14 and lever 9 bypushing the ball 20 in the direction perpendicular to the spiral slot 24against the inner wall of the spiral slot 24 when a disturbing torqueoccurring in the camshaft 1 is transferred to the movable member 17 viathe lever 9 and link 14 causing the ball 18 to be displaced in theradial slot 8 in the direction perpendicular to the spiral slot 24.

DISCLOSURE OF THE INVENTION Objects of the Invention

The prior art device suffers a problem that, in the event of such atorque disturbance as mentioned above, the ball 20 collide the innerwall of the spiral slot 24 located on either outward or inward side ofthe radial groove 8, when each ball makes point contact with the walland applies a large pressure on a localized small area of the spiralslot 24. This is a source of frictional wear of the spiral slot andcauses eventual backlashes in the ball-groove system.

A further problem is that under the disturbing torque the balls 18 and20 can generate axial thrusts in the camshaft 1 via the retainers 19 and21, radial slot 8, and spiral slot 24, which may cause an axial backlashof the link 14.

A still further problem is that it is difficult to provide a large phaseangle variation between the camshaft 1 and the drive plate 3 in thestructurally complex link mechanism 14 of the prior art device.

The present invention overcomes such prior art problems as mentionedabove by providing a phase changing device for use with an automobileengine, the device having a self-lock mechanism in which phase varyingmembers play roles of the prior art balls 18 and 20 without generatinglocalized pressure on one side of the inner circumferential walls of thegroove guides as they are displaced in the groove guides, therebypreventing frictional wear of the inner circumferential walls of thegroove guides and avoiding generation of such axial thrusts as mentionedabove. In this device a large phase angle variation can be realizedbetween the camshaft 1 and the drive plate 3.

Means for Solving the Problems

To achieve these objects the invention provides a phase changing deviceas defined in Claim 1 which has: a drive rotor driven by the crankshaftof an engine, a middle rotor integral with the camshaft of the deviceand arranged ahead of the drive rotor, a control rotor arranged ahead ofthe middle rotor and rotatable about the rotational axis common to thedrive rotor and the middle rotor, the device capable of altering therelative phase angle between the drive rotor and the camshaft byrotating the middle rotor relative to the drive rotor by providing thecontrol rotor with a torque generated by a torque means, the devicecharacterized by comprising:

curved first guide grooves formed in the control rotor, each grooveskewed with respect to a circumference of a circle centered at therotational axis;

oblique guide grooves each groove formed in the middle rotor andextending at an angle with respect to a radius crossing the groove;

second guide grooves formed in the drive rotor and skewed with respectto the circumference of a circle centered at the rotational axis of thedrive rotor,

block sections each extending along, and movable in, the respectivefirst guide;

first slide members each protruding from the respective block sectionfor engagement with, and movement in, the respective skewed guidegroove; and

phase varying members each having a second slide member that extendsthrough an escape groove formed in the middle rotor and engages therespective second guide groove so as to move in the second guide groove.

When subjected to brake action of the torque means, the control rotor isretarded in phase angle relative to the middle rotor. The phase varyingmembers move radially on the control rotor as the block sections aredisplaced in the curved first guide grooves skewed with respect to thecircumference. As the first slide members of the phase varying membersare displaced in the respective oblique guide grooves and the secondslide members are displaced radially in the respective second guidegrooves, the middle rotor integrated to the camshaft rotates relative tothe drive rotor in a manner defined by the configuration of the secondguide grooves, thereby varying the phase angle between the camshaft andthe drive rotor driven by the crankshaft.

The inventive device as defined in claim 1 is provided with a self-lockmechanism adapted to immovably lock the phase varying members, shouldtorque disturbance occur in the camshaft movement caused by reaction ofthe valve springs, thereby prohibiting relative rotational motion of themiddle rotor and the drive rotor to prevent unexpected phase variationbetween the camshaft and the drive rotor driven by the crankshaft.

(Function)

In other words, if such torque disturbance takes place, the middle rotorcoupled to the camshaft is acted upon by a torque that causes the middlerotor to rotate relative to the drive rotor. In that event, the firstslide members are acted upon by forces transferred from the engagingoblique guide grooves in radially inward directions, and the secondslide members are acted upon by forces transferred from the second guidegrooves in the substantially opposite directions. The block sections ofthe phase varying members are acted upon by radial forces from the firstand second slide members in the radially opposite directions. Theseforces skew the phase varying members in the engaging first guidegrooves and force them against the opposite inner walls of the firstguide grooves, resulting in frictional forces acting on the blocksections from the opposite sides to immovably fix the phase varyingmembers in position in the first guide grooves.

In this case, the first and second slide members protruding from theblock sections are also immovably fixed relative to the engaging obliqueguide grooves and second guide grooves. Thus, the middle rotor coupledto the camshaft is immovably fixed relative to the drive rotor, therebypreventing unanticipated phase variation that could otherwise occurbetween the camshaft and the drive rotor driven by the crankshaft.

That is, should such torque disturbance take place, the phase varyingmembers generate frictional forces via the block sections acting on theboth sides of the first guide grooves, so that frictional forces are notlocalized but distributed over different areas of the grooves.

Further, since the block sections are not spherical in shape, the blocksections will not generate forces in response to the torque disturbancethat thrust the respective rotors in the axial direction.

The inventive device as defined in claim 2 provides the first and secondslide members in the form of a shaft-like member that can roll in therespective first and second guide grooves.

(Function)

By providing the first and second slide members in the form of rollableshaft-like members, less frictional forces are generated on the wall ofthe oblique guide grooves and the second guide grooves. In addition,disturbing torques are transferred to the block sections without beingdamped by the sliding friction of the first and second slide members.

RESULTS OF THE INVENTION

The invention defined in Claim 1 will generate little local frictionswith the phase varying members in contact with the first guide grooves,thereby reducing the wear of the contact areas thereof and cluttering ofthe members.

Less axial thrusts will be generated, and hence generating reduced axialcluttering of the mechanism.

It should be noted that the phase variation mechanism can be obtained ina simple combination of phase varying members and guide grooves. Inaddition, a large phase variation angle can be realized by providingsufficiently long first guide grooves.

The invention defined in Claim 2 will generate little friction with thefirst and second slide members in sliding contact with the oblique andsecond guide grooves, thereby reducing axial cluttering of themechanism. In addition, since disturbing torques are transferredpositively to the block sections without being damped by the slidingfrictions of the first and second slide members, the block sections ofthe first guide grooves can be infallibly locked.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a phase changing device foruse with an automobile engine in accordance with a first embodiment ofthe invention, the view taken from front.

FIG. 2 is an exploded perspective view of the device taken from behind.

FIG. 3 is a front view of the device.

FIG. 4 is an axial cross section of the device taken along Line A-A ofFIG. 3.

FIG. 5 is a diagram illustrating phase varying members, and moreparticularly, FIG. 5( a) is a perspective view and FIG. 5( b) is anexploded perspective view.

FIG. 6 is a diagram showing the arrangement of guide grooves and phasevarying members in accordance the first embodiment in which the deviceis adapted to perform phase angle variation in angle retardation mode.

FIG. 7 is a vertical cross section of a control rotor of the device,taken along Line B-B of FIG. 4.

FIG. 8 is a cross section of a middle rotor taken along Line C-C of FIG.4.

FIG. 9 is a cross section of a drive rotor of the device taken alongLine D-D of FIG. 4.

FIG. 10 is a cross section of a phase variation stopper of the devicetaken along Line E-E of FIG. 4.

FIG. 11 is a diagram illustrating the self-lock mechanism of the firstembodiment, FIG. 11( a)-(c) showing its phase varying members acted uponby forces generated in cam torque disturbance.

FIG. 12 is a diagram illustrating an arrangement (referred to as phaseadvancing arrangement) for performing phase variation in the angularlyadvancing direction. More particularly, FIG. 12( a) shows the initialarrangement of the guide grooves and phase varying members of therespective rotors; FIGS. 12( c) and (d) the phase varying members actedupon by external forces caused by a cam torque disturbance.

FIG. 13 is an exploded perspective view of the phase changing device inaccordance with a second embodiment of the invention for use with anautomobile engine.

FIG. 14 is an axial cross section of the device of the second embodimentof the invention.

FIG. 15 is a cross section of a mechanism for performing relativerotation of the control rotor and the second control rotor, taken alongLine F-F of FIG. 14.

FIG. 16 is an exploded perspective view of the phase changing device foruse with an automobile engine in accordance with a third embodiment ofthe invention, the view taken from front.

FIG. 17 is an axial cross section of the device in accordance with thethird embodiment of the invention.

FIG. 18( a) shows a transverse cross section of the second control rotortaken along Line G-G of FIG. 17; FIG. 18( a), transverse cross sectionof the second control rotor taken along Line H-H of FIG. 17; FIG. 18(c), a transverse cross section of the second control rotor taken alongLine I-I of FIG. 17.

FIG. 19 shows an device of the third embodiment in operation. Moreparticularly, FIG. 19( a)-(c) respectively show the initial conditionprior to a phase variation, a condition during a phase variation, andafter a maximum phase variation;

FIG. 20 is an exploded perspective view of a phase changing device foruse with an automobile engine in accordance with a fourth embodiment ofthe invention, the view taken from front.

FIG. 21 is an exploded perspective view of the device, the view takenfrom behind.

FIG. 22 is an axial cross section of the device in accordance with thefourth embodiment of the invention.

FIG. 23( a) shows a transverse cross section of a circular eccentric camof a second control rotor, taken along Line J-J of FIG. 22; FIG. 23( b),a cross section of a cam guide plate taken along Line K-K of FIG. 22;and FIG. 23( c), a cross section of a circular eccentric cam of acontrol rotor, taken along Line L-L of FIG. 22.

FIG. 24 is a diagram illustrating the fourth device in operation, andmore particularly, FIG. 24( a)-(c) respectively show conditions of thedevice prior to a phase variation, during a phase variation; and after amaximum phase variation

SYMBOLS

-   -   40: camshaft    -   41: drive rotor    -   43: middle rotor    -   44: electromagnetic clutch (torque means)    -   45: control rotor    -   46: sprocket (drive rotor)    -   47: drive plate (drive rotor)    -   49 and 49′: oblique guide grooves    -   50: escape groove    -   51: first guide groove    -   52 and 52′: second guide grooves    -   54: torsion spring    -   57: phase varying members    -   58: block sections    -   59: first slide members    -   60: second slide members    -   67, 72, and 81: second electromagnetic clutches (torque means)    -   L1: rotational axis

BEST MODE FOR CARRYING OUT THE INVENTION

The invention will now be described in detail by way of example withreference to the accompanying drawings.

FIG. 1 is an exploded perspective view of a phase changing device foruse with an automobile engine in accordance with a first embodiment ofthe invention, the view taken from front; FIG. 2 is an explodedperspective view of the device taken from behind; FIG. 3 is a front viewof the device FIG. 4 is an axial cross section of the device taken alongLine A-A of FIG. 3; FIG. 5( a) is a perspective view and FIG. 5( b) isan exploded perspective view of phase varying members; FIG. 6 is adiagram showing the initial arrangement of the guide grooves and phasevarying members of respective rotors for performing phase anglevariation in angle retardation mode in accordance with the firstembodiment of the invention; FIG. 7 is a vertical cross section of arotational control body of the device; FIG. 8 is a cross section of amiddle rotor taken along Line C-C of FIG. 4; FIG. 9 is a vertical crosssection of a rotational driving body of the device taken along Line D-Dof FIG. 4; FIG. 10 is a cross section of a phase varying stopper of thedevice taken along Line E-E of FIG. 4; FIG. 11( a)-(c) show a self-lockmechanism of the first embodiment; FIG. 12( a)-(c) show an arrangementof phase changing device for angularly advancing direction; FIG. 13 isan exploded perspective view of the phase changing device in accordancewith a second embodiment of the invention for use with an automobileengine; FIG. 14 is an axial cross section of the device in accordancewith the second embodiment of the invention; FIG. 15 is a cross sectionof a relative-rotation-mechanism for the rotational control body and thesecond rotational control body; FIG. 16 is an exploded perspective viewof the phase changing device for use with an automobile engine inaccordance with a third embodiment of the invention; FIG. 17 is an axialcross section of the device in accordance with the third embodiment ofthe invention; FIG. 18( a) is a transverse cross section of the secondrotational control body taken along Line G-G of FIG. 17; FIG. 18( b) isa transverse cross section of the second rotational control body takenalong Line H-H of FIG. 17; FIG. 18( c) a transverse cross section of thesecond rotational control body taken along Line I-I of FIG. 17; FIG. 19is a diagram showing the device in operation, and more particularly,FIG. 19( a)-(c) respectively show the initial condition prior to a phasevariation, a condition during a phase variation, and after a maximumphase variation; FIG. 20 is an exploded perspective view of a phasechanging device for use with an automobile engine in accordance with afourth embodiment of the invention; FIG. 21 is an exploded perspectiveview of the device as viewed from behind FIG. 22 is an axial crosssection of the device in accordance with the fourth embodiment of theinvention; FIG. 23( a) shows a transverse cross section of a circulareccentric cam of a second rotational control body, taken along Line J-Jof FIG. 22; FIG. 23( b), a cross section of a cam guide plate takenalong Line L-L of FIG. 22; and FIG. 23( c), a cross section of acircular eccentric cam of the rotational control body, taken along LineL-L of FIG. 22; and FIG. 24 is a diagram illustrating the fourth devicein operation, and more particularly, FIG. 24( a)-(c) respectively showthe initial condition of the device prior to phase variation, during aphase variation, and after a maximum phase variation.

Phase changing devices shown in these figures are in accord with eitherone of the first through fourth embodiments of the invention. The deviceis integrally assembled to an engine such that the rotation of thecrankshaft is transmitted to the camshaft to synchronize opening-closingof the air suction/exhaustion valves with the rotational motion of thecrankshaft of the engine, and vary the opening-closing timing in accordwith the load and/or rpm of the engine.

Referring to FIGS. 1 through 4, there is shown an device of embodiment1, which comprises a drive rotor 41 integrally formed of a sprocketmember 46 driven by the crankshaft (not shown) and a drive plate 47. Thedrive rotor 41 is rotatably mounted on a center shaft 42 which isintegrated to the camshaft 40 of the device. A middle rotor 43 isimmovably fixed, ahead of the drive rotor 41, to the center shaft 42. Acontrol rotor 45 is rotatably mounted on the front end of the centershaft 42 and adapted to be controlled by an electromagnetic clutch 44.The drive rotor 41, middle rotor 43, and control rotor 45 are coaxialabout the axis L1.

The leading end 40 a of the camshaft 40 is securely fixed in thecircular hole 42 a of the center shaft 42. Cylindrical sections 42 c and42 d, formed before and after a pair of flange-shaped stopper protrusion42 b provided on the outer surface of the center shaft 42, are rotatablyfitted in the circular holes 46 c and 47 a of the sprocket member 46 andof a drive plate 47, respectively, to rotatably support the sprocketmember 46 and drive plate 47. The sprocket member 46 has sprockets 46 aand 46 b. The sprocket member 46 and the drive plate 47 are integrallycoupled with a multiplicity of coupling pins 48 to form a drive rotor41.

The drive plate 47 is provided with a pair of curved second guidegrooves 52. A central circular hole 47 a is formed in the drive plate47. In the first embodiment, the second guide grooves 52 are elongategrooves extending in the counterclockwise direction (as viewed from thefront) and curving radially inwardly so that the radius of the groovefrom the rotational axis L1 decreases continuously.

Formed in the disk shaped middle rotor 43 are a square axial throughhole 43, a pair of oblique guide grooves 49 skewed in the direction froman upper right side to a lower left side of the radius crossing thegrooves as viewed from before backward, and escape holes 50 each runningin parallel to the respective oblique guide grooves. The middle rotor 43is securely fixed to the center shaft 42 by fitting the flat engagingface 42 j of the center shaft 42 in the square hole 43 a of the middlerotor 43.

The control rotor 45 has a central circular hole 45 a and a pair ofcurved first guide grooves 51. In the first embodiment, the first guidegrooves 51 are elongate grooves extending in the clockwise direction (asviewed from front) and curving radially inwardly, so that the radii ofthe grooves from the central axis L1 decrease continuously. The driverotor 45 is rotatably mounted on the cylindrical section 42 e providedon the leading end of the center shaft 42 via a thrust bearing 53mounted in a recessed circular bore 45 d formed in the front end of thecircular hole 45 a.

Mounted on an engine casing (not shown) at a position ahead of thecontrol rotor 45 is an electromagnetic clutch 44 for attracting thecontrol rotor 45 when a coil 44 a is energized. Inside theelectromagnetic clutch 44 is a spring holder 55 having on the outercircumference thereof a torsion spring 54. The leading end 55 a of thetorsion spring 54 is hooked in the recess 42 f formed in the centershaft 42. The spring holder 55, center shaft 42, and camshaft 40 arecoupled integrally by passing a bolt 56 through central holes 55 b and42 g of the spring holder 55 and center shaft 42, respectively, andtightly screwing the bolt 56 into a threaded female bore 40 b formed inthe camshaft 40. Thus, the spring holder 55 and center shaft 42 arerotated together with the camshaft. The opposite ends 54 a and 54 b ofthe torsion spring 54 are securely fixed in the bore 45 b formed in thecontrol rotor 45 and in the bore 55 c of the spring holder 55 to urgethe control rotor 45 in the direction opposite to the rotationaldirection of the drive rotor 41 against the control torque provided bythe electromagnetic clutch 44.

Each of the phase varying members 57 has a block section 58, a firstslide member 59, and a second slide member 60 as shown in FIG. 5. Theblock sections 58, first slide members 59, and second slide members 60of the phase variation members 57 respectively engage the first guidegrooves 51, oblique guide grooves 49, and second guide grooves 52, asshown in FIG. 6 (escape hole 50 not shown). Each of the block sections58 is a generally oblong member having a convex surface 58 a of the samecurvature as the radially outward circumference 51 a of the first guidegroove 51 and a second concave surface 58 b of the same curvature as theradially inward circumference 51 b of the first guide groove 51, so thatthe block section 58 can freely move in the first guide groove 51.

Each of the first slide member 59 has a coupling shaft 59 a fitted inthe circular bore 58 c of the block section 58 and a slide shaft 59 bengaging the oblique guide groove 49 for movement therein. Each of thesecond slide member 60 has a coupling shaft 60 a fitted in the circularbore 58 d of the block section 58 and a slide shaft 60 b movable in thesecond guide groove 52. The coupling shaft 60 a has a smaller outerdiameter than the width of the escape hole 50 and passing through theescape hole 50 without touching it.

It is preferred to securely fix the coupling shafts 59 a and 60 a in therespective circular bores 58 c and 58 d, or rotatably mount the slideshafts 59 b and 60 b on the coupling shafts 59 a and 60 a that aresecurely fitted in the respective circular bores 58 c and 58 d, therebymaking the slide shafts 59 b and 60 b slidable in the oblique guidegrooves and the second guide grooves 52. In this configuration, theseshafts can move smoothly in the guide grooves 49 and 52, therebyreducing wear of the slide shafts 59 b and 60 b. Preferably, the slideshaft 59 b and 60 b are rollable in the guide grooves 49 and 52.Alternatively, however, they can be fixed in the circular holes 58 c and58 d together with the coupling shafts 59 a and 60 a but slidable in theguide grooves 49 and 52.

Referring to FIGS. 6 through 10, there is shown the device of the firstembodiment in phase varying operation. In the first embodiment, thedevice can operate in phase angle retardation mode in which the middlerotor 43 is rotated in the counterclockwise direction D2 from theinitial delay-free position to delay the phase angle of the middle rotor43 coupled to the camshaft 40 relative to the drive rotor 41 in rotationin the clockwise direction D1 as viewed from front. The phase varyingmembers 57 engaging the first guide grooves 51, oblique guide grooves49, and second guide grooves 52 are initially located at the mostradially outward positions possible, as shown in FIG. 6. Under theinitial condition, the control rotor 45 is urged in the clockwisedirection by the torque supplied by the torsion spring 54, and themiddle rotor 43 and control rotor 45 rotate in the direction D1 togetherwith the drive rotor 41 since the phase varying members 57 are immovablyfixed.

As the electromagnetic clutch 44 is energized, the control rotor 45shown in FIG. 7 is attracted to the electromagnetic clutch 44 and abutson the frictional members 61 (FIG. 4), when the control rotor 45 beginsto rotate in the counterclockwise direction D2 relative to the driverotor 41 and middle rotor 43. In this case, the block sections 58 ofFIG. 6 tend to rotate in the clockwise direction D1 in the first guidegrooves 51, which causes the phase varying members 57 to shift as awhole in the radially inward direction D3, thereby decreasing thedistance between the rotational axis L1 and the grooves 51.

As shown in FIG. 8, each of the oblique guide grooves 49 is skewedthrough an angle of δ with reference to Line L2 connecting therotational axis L1 and the respective axes of the first slide shafts 59b in the angularly advancing direction (that is, in the clockwisedirection D1) relative to the drive rotor 41. The first slide shafts 59b, in engagement with the oblique guide grooves 49, are displaced in thegrooves 49 in the radially inward direction D3.

When displaced in the radially inward direction D3, the second slideshafts 60 b shown in FIG. 9 are also displaced in the counterclockwisedirection D2 in the second guide grooves 52. Then, the middle rotor 43is angularly delayed (or rotated) relative to the drive rotor 41 inaccord with the displacements of the second slide shafts 60 b in thesecond guide grooves 52. As a consequence, the phase angle of thecamshaft 40 integral with the middle rotor 43 relative to the driverotor 41 driven by the crankshaft is changed in the angularly delayingdirection (that is, counterclockwise direction D2).

It is noted that the angular delay of the middle rotor 43 relative tothe drive rotor 41 increases until the torque of coil spring 54 balancesthe torque of the electromagnetic clutch 44. The maximum angular delaycorresponds to the displacement of the second slide shaft 60 b from oneend of the second guide groove 52 to the other end.

On the other hand, if the electric current through the electromagneticclutch 44 is reduced to weaken the braking power of the control rotor45, the control rotor 45 shown in FIG. 7 is rotated backward by thetorque of the spring 54 in the clockwise direction D1 relative to themiddle rotor 43, which in turn causes the phase varying member 57 tomove radially outwardly (in the direction opposite to D3).

In this case, the guide grooves 49 are acted upon by forces from thefirst slide shafts 59 b sliding in the oblique guide grooves 49, and thegrooves 52 from the second slide shafts 60 b moving in the second guidegrooves 52 in the clockwise direction D1. Accordingly, the middle rotor43 is rotated in the angularly advancing direction (or clockwisedirection D1) relative to the drive rotor 41 rotated by the crankshaft,thereby restoring possibly the initial maximum phase angle between thecamshaft 40 and the drive rotor 41.

Incidentally, as shown in FIG. 10, a pair of stopper protrusions 42 bformed on the center shaft 42 engage the stopper recess 47 a formed inthe drive plate 47. When the block sections 58, first slide shafts 59 b,and second slide shafts 60 b assume their initial positions prior to anyphase variation or positions at the maximum phase variation, the tips 42b 1 and 42 b 2 of the stopper protrusions 42 b touch respective endportions 47 a 1 and 47 a 2 of the respective stopper recesses 47 a toserve as stoppers. Thus, they prevent the block sections 58, first slideshafts 59 b, and second slide shafts 60 b from directly colliding therespective first guide grooves 51, oblique guide grooves 49, and secondguide grooves 52, thereby relieving their collision impact.

Referring to FIG. 11, there is shown a self-lock mechanism forpreventing the relative phase angle of the middle rotor 43 relative tothe drive rotor from being changed if the middle rotor 43 is subjectedto an abrupt disturbing torque from the camshaft 40. In the event thatthe middle rotor 43 in rotation in the clockwise direction D1 togetherwith the drive rotor 41 and control rotor 45 is subjected to adisturbing torque from a valve spring in the counterclockwise directionD2 via the camshaft 40, as shown in FIG. 11( a), the oblique guidegrooves 49 of the middle rotor 43 tend to rotate in the direction D2relative to the drive rotor 41 and the control rotor 45.

Since the oblique guide grooves 49 are skewed by angle δ in theclockwise direction with respect to Line L2 connecting the rotationalaxis L1 and the respective axis of the first slide shafts 59 b, if thefirst slide shafts 59 b are subjected to such disturbing torque from theoblique guide grooves 49 in the direction D2, the torque exerts forceson the first slide shafts 59 b in the radially outward directions F1.

On the other hand, the second slide shafts 60 b are acted upon by forcesin the counterclockwise direction D2 via the first slide shafts 59 b andthe block sections 58 coupled thereto. However, since the first slideshafts 59 b engage the second guide groove 52 which are curved radiallyinwardly, the second slide shafts 60 b are moved in the radially inwarddirection in the second guide grooves 52, rather than along thecircumference of the drive rotor 41.

As a consequence, the block section 58 is directed in thecounterclockwise direction D4 by the radially outward components of theforces F1 acting on the first slide shafts 59 b and by the radiallyinward components of the forces F2 acting on the second slide shafts 60b, as shown in FIG. 11( c). Thus, the convex surfaces 58 a of the blocksections 58 are forced against the radially outward circumferences 51 aof the first guide grooves 51 near the respective first slide shafts 59b. Further, the concave surfaces 58 b are forced against the radiallyinward circumferences 51 b of the first slide grooves 51 near the secondslide shafts 60 b. As a result, frictions take place on both of theradially inward and outward circumferences of the first guide grooves51, rendering the block sections 58 immovably locked in the respectivefirst guide grooves 51.

Contrary to the foregoing case, in the event that the middle rotor 43 isurged in the angularly advancing direction D1 relative to the driverotor 41 and control rotor 45 by a disturbing clockwise torquetransferred from the camshaft 40, the first slide shafts 59 b are actedupon by radially inward forces and the second slide shafts 60 b areacted upon by radially outward forces. As a consequence, the blocksections 58 are deflected in the opposite clockwise direction D4,thereby generating frictions on both the radially inward and outwardsides of the circumference of the first guide grooves 51, which causesthe middle rotor 43 to be immovably locked in the first guide groove 51.

As described above, if a disturbing torque is inputted to the middlerotor 43 from the camshaft 40 shown in FIG. 1, the phase varying members57 are immovably locked and so is the middle rotor 43 relative to thedrive rotor 41, thereby keeping the relative phase angle between themunchanged. It should be noted that in this case the locking frictionalforces are distributed over the radially inward and outwardcircumferences 51 a and 51 b of the first guide grooves 51, frictionalwear of the guide grooves 51 and phase varying members 57 is reduced.

Next, referring to FIGS. 12( a)-(c), there is shown the arrangements ofthe guide grooves 51, 49′, and 52′ of the respective rotors and of thephase varying members 57 for a case where the middle rotor 43 hasinitially no angular displacement relative to the drive rotor 41 butwill be advanced in the angularly advancing direction as needed. Theiroperations will now be described below.

As shown in FIG. 12( a), the oblique guide grooves 49′ of this phasechanging device are skewed through an angle of δ towards the angularlydelaying direction (that is, in the opposite counterclockwise directionD2 in contrast to the first embodiment) with reference to the Lines L2connecting the rotational axis L1 and the respective axes of the firstslide shafts 59 b. The configuration of this phase changing device isthe same as that of the foregoing device for performing phase anglevariation in angle retardation mode, except that the second guidegrooves 52′ extend in the clockwise direction D1 (opposite to thedirection of the first embodiment).

When a brake is applied to the control rotor 45, the block sections 58are displaced in the first guide grooves 51 to move the phase varyingmembers 57 in the radially inward direction D5 as shown in FIG. 12( a).In this case, the first slide shafts 59 b are displaced in therespective oblique guide grooves 49′, and the second slide shaft 60 bare displaced in the clockwise direction D1 and in the radially inwarddirection D5. As a consequence, the first slide shafts 59 b and secondslide shafts 60 b are acted upon by forces from the respective obliqueguide grooves 49 and the second guide grooves 52′, which causes themiddle rotor 43 having the groove 49′ to be rotated in the angularlyadvancing clockwise direction D1 relative to the drive rotor 41, andhence advancing the phase angle of the camshaft 40 relative to the driverotor 41. If the braking on the control rotor 45 is reduced, the phaseangle of the camshaft 40 is retarded relative to the drive rotor 41 bythe backward torque of the torsion spring 54.

In the event that oblique guide grooves 49′ of the middle rotor 43 areurged to move in the counterclockwise direction D2 relative to the driverotor and the control rotor 45 by a disturbing torque transferred fromthe camshaft 40, the first slide shafts 59 b are acted upon by forces F3in the radially outward directions, since each of the oblique guidegrooves 49′ is skewed by the angle δ with respect to Line L1 thatconnects the axis L1 and the axis of the first slide shaft 59 b. On theother hand, in response to the forces F3, the second slide shafts 60 bare pulled radially inwardly (that is, along the curved second guidegroove 52) by the block sections 58 coupled thereto (by forces F4 say asshown in FIG. 12) rather than pulled in the circumferential direction ofthe drive rotor 41.

As a consequence, the motions of the block sections 58 are deflected inthe counterclockwise direction D6 by the radially outward component ofthe forces F3 acting on the first slide shafts 59 b and the radiallyinward components of the forces F4 acting on the second slide shafts 60b, as shown in FIG. 12( c). On the other hand, in the event that themiddle rotor 43 is acted upon by a torque that urges the camshaft 40 torotate in the angularly advancing direction D1 relative to the driverotor and control rotor 45, the motions of the block sections 58 aredeflected not in the counterclockwise direction D6 but in the oppositeclockwise direction. As a consequence, the block sections 58 generatefrictional forces between themselves and the radially inward and outwardcircumferences (52 a and 512 b) of the first guide grooves 51, whichcauses the phase varying members 57 to be immovably locked, therebycausing the middle rotor 43 to be immovably locked relative to the driverotor.

Next, referring to FIGS. 13 through 15, there is shown a phase changingdevice for use with an automobile engine in accordance with the secondembodiment of the invention. In the second embodiment, a secondelectromagnetic clutch mechanism 62 is employed to restore phase anglein place of the coil spring 54 used in a phase angle restorationmechanism in the first embodiment. This mechanism makes it possible toprovide phase variation in the opposite direction as compared with thefirst electromagnetic clutch 44.

The second electromagnetic clutch mechanism 62 of the second embodimentincludes: a second control rotor 63 arranged ahead of the control rotor45, a multiplicity of planet gears 64 in engagement with a gear 63 athat protrudes backward from the second control rotor 63 and with a gear45 c provided in the circular hole formed in the front end of thecontrol rotor 45, a thrust bearing 65, a spring holder 66, and a secondelectromagnetic clutch 67. The control rotor 45 is rotatably supportedon the cylindrical section 42 l of the center shaft 42 by rotatablyfitting the cylindrical section 42 l in the circular hole 45 a of thecontrol rotor 45. The second control rotor 63 is rotatably mounted onthe leading end of the center shaft 42 by securely fixing the smallcylindrical section 42 h of the center shaft 42 in the circular hole 65a of the thrust bearing 65 fitted in the recessed circular hole 63 b ofthe second control rotor 63.

The control rotor 45 and second control rotor 63 are spaced apart in theaxial direction. The spring holder 66 is fitted on the step section 42 iformed at the leading end of the center shaft 42. A bolt 56 is tightlyscrewed in the threaded bore 40 b of the camshaft 40 to prevent theconstituent elements 16 of the second control rotor 63 and the like fromcoming off. The electromagnetic clutch 67 is secured on the enginecasing (not shown) facing the second control rotor 63. The secondembodiment are the same as the first embodiment in other respects.

Under the initial condition where there is no phase variation, thesecond control rotor 63 rotates in the clockwise direction D1 togetherwith the control rotor 45 and drive rotor 41. If the electromagneticclutch 44 is energized to vary the phase angle of the middle rotor 43relative to the drive rotor, braking action of the electromagneticclutch 44 takes place, so that the control rotor 45 rotates in thecounterclockwise direction D2 relative to the middle rotor 43 which isin rotation in the clockwise direction D1, and the phase varying members57 are moved radially inwardly. Thus, the phase angle of the middlerotor 43 is changed in the angularly delaying direction(counterclockwise direction D2) relative to the drive rotor 41, as inthe first embodiment.

On the other hand, if the second electromagnetic clutch 67 is energized,the second control rotor 63 is rotated in the counterclockwise directionD2 relative to the control rotor 45 rotating in the clockwise directionD1. In this case, the control rotor 45 rotates in the clockwisedirection D1 relative to the middle rotor 43 due to the counterclockwiserotation (in the direction D7) of the planet gears 64 between the gears64 a and 45 c. As a result, the phase varying member 57 is movedradially outwardly, causing the phase angle of the middle rotor 43 to beadvanced (in the clockwise direction D1) relative to the drive rotor 41,as in the first embodiment.

Referring to FIGS. 16 through 19, there is shown a phase changing devicein accord with the third embodiment of the invention. The thirdembodiment is a modification of the second embodiment, in which twoelectromagnetic clutches are used as in the second embodiment, one forthe phase varying mechanism and another for the phase angle varyingmechanism. In addition, the planet gears of the phase angle restorationmechanism used in the second embodiment are replaced with slide pins.

Third embodiment includes a second middle rotor 68, second control rotor69, thrust bearing 70, spring holder 71, electromagnetic clutch 44, andsecond electromagnetic clutch 72, all arrange ahead of the control rotor45 in the order mentioned.

As shown in FIG. 18( a)-(c), the control rotor 45 has a central circularhole 45 a and a pair of third curved guide grooves 73 formed in thefront end thereof, each extending in the clockwise direction D1 aboutthe rotational axis L1 and having a continuously decreasing radius. Thesecond middle rotor 68 has a central square hole 62 a and a pair ofradial guide grooves 74 formed on the opposite sides of the secondmiddle rotor 68. The second control rotor 69 has a central circular hole69 a, a recessed central circular bore 69 b formed in the front endthereof, and a pair of fourth curved guide grooves 75 formed in the rearend thereof each extending in the counter clockwise direction D2 aboutthe rotational axis L1 and having a continuously decreasing radius.

The control rotor 45 is rotatably supported on the cylindrical portion42 l of the center shaft 42 by fitting in the circular hole 45 a thereofthe cylindrical portion 42 l of the center shaft 42. The second middlerotor 68 is immovably secured on the center shaft 42 by fitting in thesquare hole 68 a thereof the second flat engaging face 42 k of thecenter shaft 42. The second control rotor 69 has a recessed circularbore 69 b that accommodates therein an embedded thrust bearing 70. Thesecond control rotor 69 is rotatably supported on the center shaft 42 bysecurely fitting the small cylindrical section 42 h of the center shaft42 in the circular hole 70 a of the thrust bearing 70. A pair of slidepins 76 slidably engage the guide grooves 73-75.

The control rotor 45, second middle rotor 68, and second control rotor69 are spaced apart in the axial direction. A spring holder 71 is fittedon the step section 42 i formed on the leading end of the center shaft42. A bolt 56 is tightened in the threaded bore 40 b formed in thecamshaft 40 to prevent the constituent elements of the second controlrotor 69 and the like from coming off the shaft. The secondelectromagnetic clutch 72 is securely fixed on the engine casing (notshown) facing the front end of the second control rotor 69. The thirdembodiment is the same as the second embodiment in other respect.

Under the initial condition where there is no phase variation (FIG. 19(a)), the second middle rotor 68 and second control rotor 69 rotate inthe clockwise direction D1 (FIG. 16) together with the control rotor 45.As in the second embodiment, the middle rotor 43 is delayed in phaseangle (the phase varied in the angularly delaying direction D2) relativeto the drive rotor due to the braking action of the electromagneticclutch 44 retarding the control rotor 45 in the counterclockwisedirection D2 relative to the middle rotor 43.

In this case, the third guide grooves 73 of the control rotor 45 rotatein the counterclockwise direction D2 relative to the second middle rotor68 and second control rotor 69, as shown in FIGS. 18 and 19, so that theslide pins 76 are moved in the radial inward direction D8 in the guidegrooves 73 and 74. The fourth guide grooves 75 are forced to move by theslide pins 76 moving in the radially inwardly. As a consequence, thesecond control rotor 69 is rotated in the clockwise direction D1relative to the second middle rotor 68.

On the other hand, as the second electromagnetic clutch 72 is energized,the second control rotor 69 (or fourth guide grooves 75) is rotated fromthe position shown in FIG. 19( c) in the counterclockwise direction D2relative to the control rotor 45 and second middle rotor 68 rotating inthe clockwise direction D1. As a consequence, the slide pins 76 aremoved radially inwardly (opposite to D8) in the guide grooves 74 and 75.The slide pins 76 moving radially outwardly force the third guidegrooves 73 such that the control rotor 45 is rotated in the clockwisedirection D1 relative to the second middle rotor 68. At the same time,the phase varying members 57 are moved radially inwardly since thecontrol rotor 45 rotates in the clockwise direction D1 relative to thedrive rotor. As a consequence, the phase angle of the middle rotor 43 isvaried in the angularly advancing direction D1 relative to the driverotor 41, as in the second embodiment.

Referring to FIGS. 20 through 24, there is shown a phase changing devicefor use with an automobile engine in accordance with the fourthembodiment of the invention. As in the second and third embodiments, thethird embodiment has two electromagnetic clutches in the phase anglevarying mechanism and phase angle restoration mechanism. In addition,the third embodiment utilizes a circular eccentric cam mechanism in thephase angle restoration mechanism.

In the fourth embodiment, there are provided a cam guide plate 77, asecond control rotor second control rotor 78, a thrust bearing 79, aspring folder 80, electromagnetic clutches 44 and 81, all arranged aheadof the control rotor 45 in the order mentioned.

The control rotor 45 is provided with a recessed circular bore 45 fformed in the front end thereof, and a circular eccentric cam 45 hformed around the circular hole 45 a. The circular eccentric cam 45 hextend forward from the bottom 45 g of the recessed circular bore 45 f,and has a central axis L2 offset from the rotational axis L1 by adistance S1.

The second control rotor 78 has a central??? circular hole 78 c and acircular eccentric cam 78 b formed around the circular hole 78 c whichprotrudes backward from the rear end 78 a of the second control rotor 78and has a central axis L3 offset from the axis L1 by the distance S1.

On the other hand, the cam guide plate 77 is provided on the oppositeends thereof with recessed oblong bores 77 a and 77 b in which thecircular eccentric cams 45 h and 78 b are slidably fitted. The cam guideplate 77 is also provided with a generally square through hole 77 c thatextends in the direction perpendicular to the longest diameter of theoblong bores 77 a and 77 b.

The center shaft 42 is passed through the circular through hole 45 a ofthe control rotor 45 such that the control rotor 45 is rotatablysupported on the cylindrical section 42 l of the center shaft 42. Theinner circumference of the square hole 77 c of the cam guide plate 77 ismounted on the second flat engagement surface 42 k of the center shaft42 such that the cam guide plate 77 is not rotatable relative to thecenter shaft 42 but slidable on the horizontal surface 42 k 1 of thesecond flat engagement surface 42 k in the direction parallel to thelong sides of the square through hole 77 c. The second control rotor 78is rotatably supported on the center shaft 42. This can be done byfitting on the small cylindrical section 42 h of the center shaft 42 theinner circumference of the circular hole 79 a of the thrust bearing 79embedded in the recessed circular bore 78 d.

The circular eccentric cams 45 h and 78 b engage the respective recessedoblong bores 77 a ad 77 b. Thus, when the control rotors 45 and 78rotate relative to the cam guide plate 77, the circular eccentric cams45 h and 78 b slidably reciprocate in the respective recessed oblongbores 77 a and.

The control rotor 45, cam guide plate 77, and second control rotor 78are spaced apart in the axial direction. The spring holder 80 is fittedin the recess 42 i formed in the front end of the center shaft 42. Abolt 56 is tightly screwed in a threaded bore 40 b of the camshaft 40 toprevent the elements of the second control rotor 78 and the like fromcoming off the camshaft 42. The second electromagnetic clutch 81 issecurely fixed on the engine casing (not shown) facing the front end ofthe second control rotor 69. The fourth embodiment is the same as theforegoing embodiments in other respects.

As shown in FIGS. 23( a)-(c), under the initial condition where there isno phase variation, the cam guide plate 77 is located at the far rightend inside the recessed circular bore 45 f, where the circular eccentriccam 78 b is positioned with its central axis L3 inclined at an angle ofθ in the clockwise direction D1 with reference to the horizontal axis L4as shown in FIG. 23( a), while the circular eccentric cam 45 h ispositioned with its central axis L2 inclined at an angle of θ in thecounterclockwise direction D2 with reference to the horizontal axis L4,as shown in FIG. 23( c).

Under the initial condition where there is no phase variation, the camguide plate 77 and second control rotor 78 rotate in the clockwisedirection D1 together with the control rotor 45. Under the brakingaction of the electromagnetic clutch 44 on the control rotor 45, thecontrol rotor 45 is rotated relative to the middle rotor 43, as in thesecond and third embodiments, thereby varying the phase angle of themiddle rotor 43 in the angularly delaying direction (that is, in thecounterclockwise direction D2).

Under such condition, the circular eccentric cams 45 h integrated to thecontrol rotor 45 is rotated from the position shown in FIGS. 23( c) and24(a) about the rotational axis L1 in the counterclockwise direction D2with reference to the horizontal axis L4, possibly through the maximumpermissible angle of 180°-θ. At the same time, the circular eccentriccam 45 h slidably moves upward inside the oblong bore 77 a until thecentral axis L2 moves past the vertical axis L5, and then movesdownwardly, so that the cam guide plate 77 is displaced to the leftuntil it reaches, in the case of maximum displacement, the left end ofthe inner circumference of the recessed bore 45 f.

In this case, the circular eccentric cam 78 b is subjected to theexternal force applied thereto by the oblong bore 77 b of the cam guideplate 77 and rotates in the clockwise direction D1 about the rotationalaxis L1 from the position shown in FIGS. 23( a) and 24(a) andreciprocates up and down inside the oblong bore 77 b. As a consequence,the second control rotor 78 which is integral with the circulareccentric cam 78 b rotates in the clockwise direction D1 relative to thecontrol rotor 45 until the central axis L3 of the circular eccentric cam78 b is possibly inclined to the maximum permissible angle of 180°-θ inthe clockwise direction D1 with reference to the horizontal axis L4.

On the other hand, when the second electromagnetic clutch 81 isenergized, the second control rotor 78 (circular eccentric cam 78 b) isrotated in the counterclockwise direction D2 relative to the controlrotor 45 which is rotating in the clockwise direction D1, therebyslidably reciprocating up and down on the inner circumference of theoblong bore 77 b. As a consequence, the cam guide plate 77 is displacedto the right (in the direction opposite to the direction D9) until itreaches the right end of the recessed circular bore 45 f. Because of therotational motion of the circular eccentric bore 45 h in the clockwisedirection D1 under an external force applied thereto by the oblong bore77 b of the cam guide plate 77, the control rotor 45 is rotated in theclockwise direction D1 relative to the second control rotor 78. Sincethe control rotor 45 rotates in the clockwise direction D1 relative tothe drive rotor 41, the phase varying members 57 are moved radiallyoutwardly. As a consequence, the phase angle of the middle rotor 43 isvaried in the angularly advancing direction relative to the drive rotor(rotated in the clockwise direction D1), as in the second and thirdembodiment.

It should be noted that in the second through fourth embodiments use ofan electromagnetic clutch for varying phase angle of the middle rotor 43eliminates need of a coil spring used in the first embodiment. Thismeans that energy can be saved by cutting off the electricity to theelectromagnetic clutch 44 soon after a required phase alteration isachieved. Accordingly, downsizing of the electromagnetic clutch 44 ispossible, since it requires a less torque.

Although a torsion spring is used in combination with an electromagneticclutch as a torque means in the first through fourth embodiments, anelectric motor can be alternatively used to directly provide the controlrotor with a torque, or still alternatively, a hydraulic pressurechamber may be used to provide the torque.

Although a thrust bearing is used between the control rotor and springholder in the first embodiment and between the second control rotor andspring holder in the second and fourth embodiment, a disc spring may bealternatively used. When a disc spring is used, a frictional torque isgenerated in the control rotor and second control rotor, whichadvantageously generates an inertial force in the control rotor when anabrupt change occurs in engine rpm, for example, and can eliminateunanticipated abrupt change in phase angle between the camshaft and thedrive rotor.

1. A phase changing device for automobile engine, having: a drive rotordriven by the crankshaft of an engine, an middle rotor integral with thecamshaft of the device and arranged ahead of the drive rotor, a controlrotor arranged ahead of the middle rotor and rotatable about therotational axis common to the drive rotor and the middle rotor, thedevice capable of altering the relative phase angle between the driverotor and the camshaft by rotating the middle rotor relative to thedrive rotor by providing the control rotor with a torque generated by atorque means, the device characterized by comprising: curved first guidegrooves formed in the control rotor, each groove skewed with respect toa circumference of a circle centered at the rotational axis; obliqueguide grooves each groove formed in the middle rotor and extending at anangle with respect to a radius crossing the groove; second guide groovesformed in the drive rotor and skewed with respect to the circumferenceof a circle centered at the rotational axis of the drive rotor, blocksections each extending along, and movable in, the respective firstguide; first slide members each protruding from the respective blocksection for engagement with, and for movement in, the respective skewedguide groove; and phase varying members each having a second slidemember that extends through an escape groove formed in the middle rotorand engages the respective second guide groove so as to move in thesecond guide groove.
 2. The inventive device according to claim 2,wherein the first and second slide members are shaft-like membersrollable in the respective first and second guide grooves.